JPH0195093A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To enable ink jet recording which gives a multicolor image with a shading part as well as a hypochromatic part and a mixed color part which have superior light fastness by using more than two different color inks including cyan and using at least more than two inks with different dye densities for cyan. CONSTITUTION:Preferably three different base colors such as yellow, magenta and cyan or four different base colors including black are used. Of these inks, at least, cyan ink to be used should consist of more than two different types of ink e.g. dark ink with high dye density and light ink with low dye density. For instance, cyan dye of phthalocyanine whose center metals are Ni, Co, Mg, etc. has some problem about sharpness in the hyperchromatic part. However, the cyan dye has excellent light fastness and does not deteriorate other dyes in the mixed color part. Furthermore, the cyan dye has almost no problem about sharpness in the hypochromatic part, so that it is a desirable dye as far as the hypochromatic requirements are concerned. The preferable cyan dye for hyperchromatic ink is, for instance, C.I. direct blue 86.199 of the copper phthalocyanine.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an inkjet recording method, and more specifically, it provides a multicolor image that has dark and light areas and has excellent light resistance in light and mixed color areas. This invention relates to an inkjet recording method.

(Conventional Technique i) The inkjet recording method is a method in which ink droplets are ejected from a nozzle of a recording head, and the ink droplets are absorbed by a recording material such as paper or cloth to record an image. This is a recording method that generates little noise, does not require special fixing processing, and is capable of high-speed recording and multicolor image recording.

Multicolor images can be recorded in yellow (Y), magenta (
This is done by subtractively mixing three primary colors of M), cyan (C), or four primary colors including black (Bk). That is, three colors of ink or four colors of ink including black are ejected from nozzles dedicated to each color of the recording head while controlling the ejection amount of each color, and each ink is applied to one pixel of the recording material. A multicolor image is recorded by mixing and absorbing the images.

(Problems to be Solved by the Invention) When forming a white color image, it is necessary to form not only color differences but also color shading, and furthermore, it is necessary to form intermediate color areas.

v: i The light area is formed using two or more types of ink with different dye concentrations, and the intermediate color is formed by mixing different inks (
Of course, it would be ideal for a multicolor image formed by (on a recording material) having shading and intermediate color areas to have various properties, especially excellent overall clarity and light resistance, but at present. No dyes have been developed that provide sufficient brightness and lightfastness at the same time.

That is, dyes that are generally excellent in sharpness tend to have poor lightfastness, while dyes that are excellent in lightfastness tend to be poor in sharpness.

Therefore, when multicolor images are formed using these dyes, sharp images tend to have poor light fastness, while images with excellent light fastness tend to have poor sharpness.

In particular, it has been reported that when a multicolor image is a clear image having light and dark areas, light fading in the light color areas is rapid, resulting in a significant deterioration in image quality in a short period of time.

Especially in this case, the light intermediate color area, i.e.
Color-mixed areas of primary color inks tend to undergo further photofading due to the interaction of dyes.

Therefore, an object of the present invention is to provide a multicolor image that is a clear image and also has excellent light resistance in light color areas and intermediate color areas.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides an inkjet recording method in which recording is performed using two or more color inks including cyan ink, and at least two or more inks having different dye concentrations for the cyan ink, wherein at least two of the cyan inks This is an inkjet recording method characterized by using different dyes between different types of ink.

(Function) In the inkjet recording method, dark colored areas are formed using ink containing a dye with a clear tone, and light colored areas and light intermediate colored areas are formed using a dye that does not accelerate the fading of other dyes and has excellent light resistance. By forming the image using an ink containing the above, it is possible to provide a multicolor image with overall excellent light fastness and clarity.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The ink used in the present invention is preferably yellow, magenta, cyan 3N, or 4N with black added thereto.
These are primary color inks, and among these inks, at least cyan ink uses two or more types: a dark color ink with a high dye concentration and a light color ink with a lower dye concentration. Dark inks form high density areas of a multicolor image, and light inks form light or mixed areas of a multicolor image.

The dyes used for dark ink are selected with clarity as the main focus.
On the other hand, dyes used for light-colored inks are selected with emphasis on light fastness and influence on other dyes.

For example, copper phthalocyanine-based cyan dyes generally have excellent light fastness and clarity in both shades, but when mixed with magenta ink, they tend to accelerate the deterioration of the light fastness of magenta ink. It is not preferred for use in light colored inks. On the other hand, even in the same phthalocyanine series, the central metal is Ni, Go, M
Cyan dyes such as G, etc. have some gaps in sharpness in dark colors, but they have excellent light fastness and do not deteriorate other dyes in mixed color areas, and in the case of light colors, there are problems with sharpness. It is preferable as a dye for light-colored inks because it has a small amount of pigment.

Examples of cyan dyes for dark ink include C, which is a copper phthalocyanine dye; Direct Blue 86.
199 and the following formula (I), those in which the substituents and central metals have the following numbers are listed as preferred specific examples.

No, 4” ”, M-(: u X1% X2, ×3
, X4-5O20CH:+No, 5...M-Cu
X,,I4-5020 ((:I2) 5C)+3
×2, X, = 11 No, 6...MsCu X,, I2, I3, I
4-5O2NHC)l(CH3) 2No, '7''・-
MsCu I1, I2, I3, I4-503 ・NI2 (C)+
3) (:2Hs) On the other hand, as a cyan dye for light cyan ink, the central metal is Ni, (:o, Mg, Sn
%Mn, etc., and has the following formula (I
), the substituents and central metals having the following numbers are listed as preferred specific examples.

I2, I3-H No, +3 ”M-Mg Xt, X4 Proverb 5
OJH(C)I2) 3clI3×2, X, -11 No, 14...M-5n X,, I2, I3,
I4-5o2NIIC2115No, 15”M-N
i Xt-if×2, I3, I4-503 ・NH
((:zlls)3No, +6 o-M-un X
, -II×2, I3, X4=SO3・NI2 (
CH3) C2115×1, I2, I3, I4-503
・Nll+ll:H(CI(3)2No, 22...
・M-Mg Xt, I2, I3, X4=SO2o
C211s other hues! 5. Even in the case of light ink, if different dyes are to be used for dark color ink and light color ink, they may be selected based on the same criteria as in the case of cyan.

Further, the v:4 light ink is not limited to two types, dark color ink and light color ink, and it is natural that ink having an intermediate density between them may be used.

The dye concentration of the dark ink depends on the color value of the dye used, but numerically it is about 0.8 to 5% by weight,
Similarly, in the case of light color ink, the content is about 0.01 to 1% by weight, and in the case of medium temperature 1 degree ink, the content is about o, i to 2.0% by weight, which is between them.

In addition to the above dyes, the ink used in the present invention may contain water as a liquid medium, water-soluble organic solvents such as polyhydric alcohols, humectants, and various other additives. The types of liquid medium and various additives, their blending ratios, etc. are all the same as those of conventional inkjet inks, and are not particularly limited.

Further, the inkjet recording method used in the present invention may be any conventionally known inkjet recording method and is not particularly limited, and the recording material used is not particularly limited either, and any recording material can be used.

(Example) Next, the present invention will be described in more detail with reference to Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 Water 50 parts Diethylene glycol 30 parts N-methyl 2-
Pyrrolidone 10 parts polyethylene glycol
The dyes shown in Table 1 below were dissolved in 10 parts of the solvent having the above composition to prepare the dark and light inks shown in Table 1 below.

(The following is a margin) γ, 1 5 L2 evening - Bundle 11 ■ - Bundle Mengyu Md11. C, 1, acid red 35
0.3% Cconc, (:, 1. Direct Blue 86 1.5% Cm1d, C, 1, Direct Blue 88 0.6% Cd11. Said N
o, 6 Ni phthalocyanine dye 0.3% M = magenta, C nitrogen, dil: light color, c
onc, bi-dark color, mid, : Medium color IOV step printing is performed with a piezojet printer using the above insulator to obtain a single color batch and a mixed color batch of each color, and in these batches, the color tones, Light resistance and water resistance were investigated. The long-term storage stability and ejection stability of the ink were also investigated, and the results are shown in Table 2 below.

(1) Color tone is determined by (a) visual clarity judgment and (σ
) UV and V of a sample showing equal reflection density between dark and light inks
L *a*b* calculated by measuring the rs reflection spectrum
The color difference between the dyes was evaluated by ΔE1, and the case where AE''≦3 was expressed as O13, the case where ΔE'≦8 was expressed as Δ, and the case where 8<AE8 was expressed as ×.

(2) Light resistance is xenon fade meter C135F
(manufactured by Atlas Corporation) for 30 hours on the sample.
1=0.92w/yn" at 420nm) L/
Color difference ΔE before and after light irradiation @ (1, Jab@
display system), and if AE"≦10, 0, l
Δ for the case where O<AE”≦20, and 20<AE1
Cases where this is the case are indicated with an ×.

(3) Water resistance was determined by immersing the sample in still water for 30 minutes after printing, and measuring the color difference before and after.

(4) For long-term storage stability, the ink was sealed in a glass container and stored at -30℃ and 60℃ for 6 months, and the physical properties, changes in hue, and presence of foreign substances in the ink were evaluated before and after the test. .

Comparative Example 1 Cd11 in Example 1. As, Dye Tojito No,
Example 1 except that the same amount of C, 1, Direct Blue 86 was used in place of the Ni phthalocyanine dye in Example 6.
Inkjet recording was carried out in the same manner as above, and evaluation was conducted in the same manner to obtain the results shown in Table 2 below.

γ 2-1 Master value item and one disaster treatment 1 Comparative example 1 (1) Evaluation based on recorded images/color! l (i)
OO・Color g(ro)
0-・Light resistance O×・Water resistance O○ (2) Evaluation using ink oO Example 2 Using a solvent having the same composition as in Example 1, the dark and light inks shown in Table 3 below were prepared.

(The following is a blank space) Gu J 3 -F ヱλGen - Higashi 11 赳一 Bunbashira A Gua Y
C, 1, Direct Yellow 116 G, 4
1% M conc, C, 1, acid red 35
1.5%M++id, C,1, Acid Red 35 0.6%Md11. C,1
, Acid Red 35 0.3% Cconc,
C,l Direct Blue 86 1.5%Cm1
d, C, 1, Direct Blue 86 0.6
%Cd11. Said No. 12 Ni phthalocyanine dye 0.3% Bk (:, 1. Food Black 2 2
．． 5% Using the above ink, a full color image was obtained using a piezojet printer, and a visual hue evaluation and light fastness evaluation were performed, and good results were obtained in both cases.

Comparative Example 2 All of the cyan inks were created using the Ni phthalocyanine dyes No. 12, and the image formation and evaluation were performed in the same manner as in Example 2. The light fastness was good, but The overall image was dull and dark.

Comparative Example 3 All of the cyan ink was created using C, l Direct Blue 86, and the image formation and evaluation were performed in the same manner as in Example 2. The color tone was good, but the magenta light color faded. A noticeable deterioration in image quality was observed.

Examples 3 to 4 When the following inks were evaluated in the same manner as in Example 2, good results were obtained in all cases (the dye concentration was the same as in Example 1).

One implementation side l-Y C, 1, Direct Yellow 86Mcon
c, C, 1, acid red 37Maid,
(:, 1. Acid Red 37Mai1. (:,
1. Acid Red 37Cconc, C,1, Direct Blue 199Cmid, C,1, Direct Blue 199Cdil, Ni Phthalocyanine Dye (No, 10) Bk C,! , Rough-Black 2-Disaster A-Y C, 1, Direct Yellow 86Mcon
c, C, [, Acid Red 37Ml1id,
C,! , Acid Red 37Mai1. C,1
, Acid Red 37Cconc, C,I, Direct Blue 86Cmid, C,1, Direct Blue 86CdH, Ni Phthalocyanine Dye (No. 1
1) Bk C, 1, hood black 2 (effect
Effect) According to the present invention, in the inkjet recording method, the dark color portion is formed using an ink containing a dye with a clear tone,
Light-colored areas and light-colored intermediate color areas are formed using ink containing dyes with excellent light resistance and dyes that do not promote fading of other dyes, resulting in a multicolor image with excellent overall light resistance and clarity. can be provided.

Claims (1)

[Claims] (1) An inkjet recording method in which recording is performed using two or more color inks including cyan ink, at least two or more inks having different dye concentrations for the cyan ink, the inkjet recording method comprising at least two types of ink among the cyan inks. An inkjet recording method characterized by using different dyes.